When Ayesha Sherzai, MD, and Dean Sherzai, MD, first met, at a party, one of their initial conversations foreshadowed the career paths the then-young medical students would ultimately take.
“One of the first things we talked about was our grandparents, and we discovered that we both had two grandparents who suffered from dementia,” says Dr. Dean Sherzai.
Although each had already committed to studying neuroscience, their shared experiences had a profound effect on their future careers as neurologists, researchers, and scientists — and they are now codirectors of the Alzheimer’s Prevention Program at Loma Linda University Medical Center in California. While they see patients with many different neurological conditions, the vast majority of their patients are experiencing cognitive decline and memory problems.
“More than 90 percent of what we see is cognitive decline due to neurodegenerative conditions, vascular causes, traumatic head injuries, and physiological conditions,” says Dean.
The couple also works together to educate their patients and the public on the importance of lifestyle in the development — or prevention — of dementia, and on ways to improve overall brain health.
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Lifestyle Is Key to Preventing and Treating Alzheimer’s Disease
Years of studying the pharmaceutical approaches to treating brain diseases, including Alzheimer’s, led the Sherzais to look for an alternative path to prevention — what they call “the concept of preventative neurology.”
According to the Alzheimer’s Association, an estimated 6.2 million Americans age 65 and older are currently living with Alzheimer’s. There is no cure, and treatments for Alzheimer’s for the most part focus on helping people maintain mental function and manage behavioral symptoms.
The Sherzais believe that lifestyle choices play a significant role in brain health, and that by adhering to healthy habits or changing unhealthy behaviors, people can ultimately prevent Alzheimer’s disease or slow its progression.
Based on more than two decades of research, the Sherzais have determined that there are five behavioral areas that are profoundly important for keeping the brain healthy: nutrition, exercise, stress management, restorative sleep, and optimizing mental and social activity.
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Why Is Nutrition So Important?
Understanding the role of nutrition in brain health has always been a mission for the couple, who believe that what we consume can both prevent and even reverse cognitive decline.
In fact, Dr. Ayesha Sherzai is also a trained chef, who attended culinary school at night when she was completing a fellowship in vascular neurology at Columbia University in New York City.
At home, the doctors and their two teenage kids follow a plant-based nutrition program.
According to Dean, “Every meal one consumes can serve as energy, nutrients, and building blocks, or it can be a source of inflammation, oxidation, or lipid dysregulation” — which, he says, are the core drivers that determine the progression of Alzheimer’s disease.
“Over time, our nutritional choices can either allow our brains to thrive and be sharp and healthy, or they can damage the blood vessels and lead to the accumulation of harmful by-products that result in the development of cognitive impairment,” he adds.
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Diet as a Risk Factor for Alzheimer’s Disease
Scientists don’t fully understand what causes Alzheimer’s, but researchers believe that age-related changes in the brain along with genetic, environmental, and lifestyle factors all play a role in the development of the disease.
Aging is known to be the biggest risk factor for Alzheimer’s. According to the National Institutes of Health’s National Institute on Aging, the number of people with Alzheimer’s disease doubles about every five years beyond age 65, and about one-third of people age 85 and older may have Alzheimer’s disease.
Genetics also play a role, although having a family history of Alzheimer’s does not mean that you’ll get it too. You can’t stop the aging process or change your genetics, but experts, including the Sherzais, believe that adhering to a healthy lifestyle may offset the genetic risk of developing Alzheimer’s disease.
Diet has long been understood to affect heart health and play a role in chronic illnesses such as diabetes and cancer. And more recently, research has suggested that what you consume can have a major effect on keeping your brain healthy as well.
Several conditions known to increase the risk of cardiovascular disease — such as diabetes, high cholesterol, and high blood pressure — are known to increase the risk of developing Alzheimer’s disease. According to the Alzheimer’s Association, autopsy studies have shown that as many as 80 percent of individuals with Alzheimer’s also have cardiovascular disease.
So, it makes sense that a heart-healthy diet could also help protect brain health.
Evidence That the Mediterranean Diet Is Good for Brain Health
In the mid-1950s, researchers began to investigate why heart attack rates were higher in the United States and northern European countries and lower in Mediterranean countries and Japan. This led to the Seven Countries Study, which followed 12,763 middle-aged men for more than 50 years.
Among their findings was that diets characterized by plant foods and fish were associated with lower incidences of coronary heart disease and greater survival rates, compared with Western diets that included large amounts of animal foods and sugar.
In 1993, the Oldways organization, the Harvard School of Public Health, and the World Health Organization introduced the concept of the Mediterranean diet and defined it as “a very healthful way to eat.”
Over the years, numerous studies have shown that the Mediterranean diet can be beneficial for the brain.
A study published in June 2021 in Neurology found that a regular Mediterranean-style diet may protect against protein buildup and brain shrinkage that can lead to Alzheimer’s disease. Researchers examined the diets of 512 subjects, 169 of whom were cognitively healthy and 343 of whom were identified as at risk for Alzheimer’s disease, either due to having subjective memory impairment, mild cognitive impairment (a known precursor to Alzheimer’s), or a first-degree relative who had the disease.
People who often ate foods typical of the Mediterranean diet, such as fish, vegetables, and fruit, and only occasionally ate foods not typical of the Mediterranean diet, such as red meat, received the highest scores in tests of their cognitive skills. In memory tests, those who did not follow a Mediterranean-style diet closely scored worse than those who did.
Furthermore, those who did not follow the diet had higher levels of biomarkers for beta-amyloid and tau proteins (hallmarks known to drive the symptoms of the disease) in their cerebrospinal fluid, compared with those who regularly ate a Mediterranean diet.
Finally, the study’s authors found a significant positive correlation between a closer adherence to the Mediterranean diet and higher volume of the hippocampus — the area of the brain that is considered the control center of memory and is known to shrink early on and severely with Alzheimer’s disease.
While more research is needed to understand the mechanisms by which the diet protects the brain from protein buildup, the study suggests that people may be able to reduce their risk of developing Alzheimer’s disease just by incorporating more elements of the Mediterranean diet into their daily diets.
An earlier study, published in May 2018 in Neurology, found that adherence to the Mediterranean diet may provide up to three and a half years of protection against brain aging and Alzheimer’s disease.
DASH Diet Also Shown to Benefit Brain Health
Another diet shown to benefit brain health is the Dietary Approaches to Stop Hypertension (DASH) diet, which was developed in the early 1990s after the National Institutes of Health began funding research projects to see whether specific dietary interventions were useful in treating hypertension.
The DASH diet promotes the consumption of foods that are rich in potassium, calcium, and magnesium, with a focus on grains, vegetables, fruits, and low-fat dairy products. In addition, the diet limits the intake of saturated fatty acids, total fat, cholesterol, and sodium.
It’s not surprising that the DASH diet could be beneficial for the brain, since cardiovascular health is linked to protecting your brain against strokes and dementia.
MIND Diet Combines Mediterranean and DASH Diet Components
When a group of researchers wanted to create a diet specifically to help improve brain function and prevent dementia, they combined foods from the Mediterranean and DASH diets that had been shown to benefit brain health. The diet they came up with is called the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND).
According to a study published in September 2015 in Alzheimer’s & Dementia, this newly developed diet lowered the risk of Alzheimer’s disease by as much as 53 percent in participants who adhered to the diet rigorously, and by about 35 percent in those who followed it moderately well.
Researchers also found that the MIND diet was strongly associated with slower cognitive decline and had greater estimated effects than either the Mediterranean diet or the DASH diet.
A review study published in November 2019 in Advances in Nutrition that examined 56 research articles found that higher adherence to the Mediterranean, DASH, or MIND diets is associated with less cognitive decline and a lower risk of Alzheimer’s disease, with the strongest associations being observed for the MIND diet.
Diet and Alzheimer’s Treatment
There is no cure for Alzheimer’s. But we know that changes in the brain can occur years before the first symptoms appear. These early brain changes suggest that there’s a window of opportunity to prevent or delay symptoms of dementia through lifestyle modifications, including diet.
Researchers are also beginning to explore the relationship between the gut microbiome — the viruses, bacteria, and other microbes in the digestive system — and the onset and progression of Alzheimer’s disease.
Changes in the gut microbiome as we age have been linked to disruptions in the immune system, persistent inflammation, and chronic diseases, including neurological disorders such as Alzheimer’s. Identifying the good and bad microbes could lead to new ways to predict and treat Alzheimer’s disease.
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To recap, the three diets that have been associated with the possibility of Alzheimer’s prevention are the Mediterranean, DASH, and MIND diets.
The MIND diet combines elements of the DASH and Mediterranean diets, emphasizing plant-based foods and a limited intake of animal foods and foods high in saturated fat. In addition, the MIND diet encourages the consumption of berries and green leafy vegetables, which are known to be neuroprotective.
According to the Sherzais, following an unprocessed, predominantly plant-based diet is the most powerful tool currently available in the fight against Alzheimer’s disease.
Q&A With Drs. Ayesha and Dean Sherzai on What They Eat to Keep Their Brains Healthy
Everyday Health: What does a typical day of eating look like for you?
Ayesha Sherzai: Breakfast usually starts with omega-rich muffins made with rolled oats, hemp seeds, flaxseeds, walnuts, and bananas — they are incredibly healthy and tasty — or I may have oats with blueberries. On the weekend, breakfast could be a chickpea omelet.
Lunch is either a sandwich made of whole-wheat bread, tempeh, and lots of greens and other vegetables, or a burrito made with scrambled tofu, black beans, salsa, and avocado. On other occasions, lunch could be plant-packed pasta or a plant-based burger made with beans and beets. The burger is absolutely our kids’ favorite.
Dinner is usually light, with either a healthy tomato or pea soup or a salad. If we want something more formal, we may have cauliflower steaks with walnut sauce.
EH: Why is this the diet you follow?
Dean Sherzai: We follow this diet because some of the largest studies in the world, some of which we have been involved with, have repeatedly demonstrated that a diet focused and centered on whole and plant-based foods is by far the healthiest diet and can by itself reduce the risk of Alzheimer’s by more than 50 percent.
EH: What’s your favorite healthy snack and why?
AS: My favorite is a mixture of blueberries and walnuts.
Although I don’t believe in promoting superfoods, this powerful combination is a super snack for the brain. Blueberries have been shown to have powerful anti-inflammatory properties, and they are one of the best antioxidant foods out there.
All nuts are a good choice, mostly because of their minerals and protein, but walnuts are especially great because of their high omega-3 content.
EH: How about your go-to quick breakfast? Why?
AS: Overnight oats is a quick and easy one. Among the ingredients I use are oats, cinnamon, flaxseeds, sunflower seed butter, hemp seeds, and soy milk. The recipe is in our book, and the kids absolutely love it.
EH: When you’re feeling run down, which foods or drinks do you rely on to boost your energy? Why?
AS: We keep a lot of fruits and vegetables for snacks at all times. We like eating apples, oranges, cucumbers, carrots, and celery. We usually have some almond butter with them, and it serves as a booster when we feel down. The water content of the fruits and veggies, along with the high-nutrient good fats from the nut butter, is a fantastic combination that really keeps us going for hours.
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EH: Is there a cooking method or technique that you gravitate toward? Or one you avoid? Why?
AS: We love baking. Baking has the benefits of cooking without the need for additives and oils. And baking makes food taste so delicious.
EH: How do you treat yourself?
DS: My personal favorite is Ayesha’s blueberry cobbler, which is mind-blowingly tasty. That’s something I go for at least once a week.
EH: What’s one healthy habit you wish you practiced more often? Why?
DS: Getting the eight hours of sleep that you are supposed to get. Those are probably the most important eight hours in your day. During deep, restorative sleep, your brain organizes memories and helps transfer them into long-term memories. But even more important, the brain’s glymphatic system cleanses the brain and gets rid of the bad connections and the waste produced during the day.
Sleep is profoundly important. You can condition the brain to sleep at a particular time by creating a trigger — going to bed at the same time every night and getting up eight hours later, irrespective of any circumstances.
EH: Are there any foods you never eat? Why?
DS: Processed carbohydrates, meats, and dairy products, including dairy-based cheeses.
The processed carbs because they provide the brain with high quantities of simple sugars that overwhelm the brain cells’ ability to manage glucose, they cause inflammation, and they actually age the neurons.
The meat and cheese for many reasons, but the biggest one is that they are the highest sources of saturated fat in our diet, and saturated fat, over time, is the most destructive force to the billions of blood vessels in the brain — the energy utilization system in the neurons. Saturated fat is also the main source of oxidative and inflammatory damage in the body.
EH: What’s your strategy when eating out?
AS: Eating healthy does not mean you have to deprive yourself of fun and tasty excursions to some wonderful restaurants. But it does require some planning and strategizing. Choose a restaurant with healthy options. If you don’t have the choice of picking the restaurant ahead of time, perhaps the chef would be willing to make some minor adjustments that can make some of their dishes healthier. Instead of fried, ask for baked; instead of cheese, ask for avocado. Today most restaurants are aware of the health requirements of their guests and are willing to adjust.
EH: Wine with dinner: Yes or no? Why?
DS: The fact is that the amount of alcohol that is healthy for the brain is zero. Alcohol does not have brain health benefits.
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EH: What’s one small change you’ve made — dietary or otherwise — to help reduce the risk of Alzheimer’s?
AS: I’ve become a good label reader. By reading labels, we can see things we would never have noticed before — things that could injure the brain are in every packaged item. Once you start reading the labels, you can see the chemicals, the sugar, and the saturated and trans fats. Overnight, you become aware of all the harm around you, and you take control of your brain’s health journey.
EH: What’s one small change anyone can make to help better manage Alzheimer’s?
AS: Once someone is afflicted with Alzheimer’s disease, it is critical that everyone, including the person who has the disease, is filled with love and memories. It is critical that the anxiety and fear that accompanies this disorder is met with love. Everyone must see the person in their beautiful totality of life experiences and joys, and not as a series of mistakes, losses, and fears, or anger. These latter elements are just small parts of the disease and have nothing to do with the person.
So the small change is in perspective: Focus on the greater life and not the small challenges and changes that come with the disease.
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EH: Any final thoughts on the link between eating choices and brain health?
DS: In the last decade or so, we have realized that the genetics of Alzheimer’s disease and all the risk factors have to do with the brain’s ability to withstand negative, lifelong assault.
The biggest proven risk factor for Alzheimer’s is age, and that’s not something we control.
But what we put into our bodies in the way of food is something we can control, and we’ve seen that eating the right types of food — those that are not processed, that are whole and plant-centered, that do not contain saturated fat and processed sugars, and that provide protein, natural vitamins, and minerals — can protect the brain with every meal. This is the magic of eating a mostly if not completely whole-food, plant-based diet.